I'd not go with a VSD on any sort of an agitator/beater drive motor and especially with something that has the viscosity of ice-cream.
Reason I say that, is because you need to be able to get this product moving for a start, this is where you need the initial "oomph" from a DOL starter, to get the drive unit turning in the first place.
This is only my thoughts on this, I could be way wrong too, I've worked with milk vat agitators in 22,000L refrigerated vats before and getting the blades of the agitator to turn first off with a VSD on it, was just about impossible.
What you need to think about is the amount of force required to get that beater turning.
Hope that this of some help.